React: Is it bad practice to import a child component directly rather than pass in as a dependency?

I may be over thinking this, but I am curious if importing a child component directly is bad practice with regards to coupling and testing.

Below is a simple example:

import Header from './header.jsx';

class Widget extends React.Component {
    render() {
        return (
            <div>
                <Header></Header>
                <div>{this.props.importantContent}</div>
            </div>
        )
    }
}

To me it looks like there is now coupling between Widget and Header. With regards to testing, I don't see an easy way to mock the Header component when testing the Widget component.

How do other larger React apps handle cases like this? Should I pass Header in as a prop? If using react-redux, I can inject header with the Connect method like below to reduce boilerplate. Is that sound?

import { connect } from 'react-redux';
import Header from './header.jsx';

class Widget extends React.Component {
    render() {
        return (
            <div>
                {this.props.header}
                <div>{this.props.importantContent}</div>
            </div>
        )
    }
}

const mapStateToProps = state => {
  return {
    header: Header
  }
}

export default connect(mapStateToProps)(Widget)

I am interested is simple doing what the community is generally doing. I see that one solution is doing shallow rendering to test on the main part of the component and not the child components using something like Enzyme.

Thoughts or other ideas?